It is generally known that the concentration of estrogen steroids in the female increases appreciably during pregnancy. It is also well established that the stage, as well as the fact of pregnancy, may be determined by measuring the amount of estrogen steroids present in the urine. Besch et al U.S. Pat. No. 3,615,229, issued on Oct. 26, 1971, for "Use of Oxalic Acid for the Hydrolysis of Steriod Conjugates in Pregnancy" discloses a method for the determination of pregnancy estrogen concentration comprising the hydrolysis and cleavage of conjugated steroids found in urine by treating with organic acids. The estrogens thereby liberated may then be measured under standard colorimetric methods by comparison with standard concentrations of estriol. However, this method has the disadvantage of necessitating time consuming steps such as color development and color extraction.